Effect of passivation annealing on the electromigration properties of hybrid bonding stack

This paper presents electromigration results on a hybrid bonding-based test vehicle to study the impact of bonding and passivation annealings on backend of line robustness. Black's parameters extraction leads to typical values of Cu-based interconnects. Electromigration lifetime remains the same whatever the bonding annealing conditions but a significant influence of passivation annealing is observed. Chemical analyses evidence the effect of the annealing atmosphere. A discussion is lead on the chemical species concentration at different locations of the stack and the reduction of the Time to Failure with passivation final annealing.